Architectural, industrial maintenance, decorative, protective or other coatings are commonly made or used with organic solvents that evaporate during the application of the coating. These solvents can escape into the atmosphere as volatile organic compounds (VOCs). VOCs may be a health, a safety or an environmental hazard and may need to be mitigated or removed from coating systems. Waterborne coatings, though significantly lower in VOCs than solventborne coatings, may also have appreciable VOC levels from the use of coalescing solvents or other agents in their composition.
It is possible to use organofunctional silanes in waterborne, solventborne and other coating systems to improve the properties (adhesion, solvent resistance, weatherability, etc.) of the coating. The use of organofunctional silanes as crosslinkers or adhesion promoters in these systems can contribute to VOCs through the action of water on a hydrolyzable silane. Typical commercial organofunctional silanes are supplied as silane esters and therefore release alcohols upon hydrolysis. These alcohols, such as methanol, ethanol, etc., are typically VOCs.
The preparation of hydrolyzable organofunctional silanes with leaving groups that are not volatile (or much less volatile than alcohols) is desirable to lower or eliminate VOCs in coating compositions containing organofunctional silanes. The prior art does not address the use of silane containing organofunctional groups with reduced VOCs. Accordingly, there exists a need for improved organofunctional silane adhesion promoters and/or crosslinkers to create coatings that have lower VOCs emissions.